What to look for on US election night

Election day is on Tuesday but Americans might have to wait longer to learn who their next president will be.

The timing of a Kamala Harris or Donald Trump victory depends on two factors: how fast states count their ballots and how close the results are. Each state has its own rules for processing and counting ballots.

As polls close across the country — first on the east coast — and results start to come in, news agencies and broadcasters will project the winner of each state and the District of Columbia at the presidential level, as well as races for the US Senate and House of Representatives. The Financial Times will report results based on calls from the Associated Press.

The most important number of election night is 270, the electoral college votes needed to clinch the presidency. Expect a long night on Tuesday.

Will we know the winner on the night?

This is unlikely.

Polling suggests the results in battleground states will be close, meaning it could take days for a winner to be declared. Some states are also slower to count ballots than others.

An additional complication could be any legal challenges to a state’s results, which could drag out the declaration of a winner. The Trump campaign and its allies have already started to cast doubt on the integrity of the election.

The Harris campaign has predicted Trump will declare victory before the presidential race has been called.

The first polls close on election day at 6pm eastern time in some counties in Indiana and Kentucky, with the last polls closing at midnight ET in Alaska.

If swing states move quickly to count and the vote is not as close as polls predict, the result could be clear on Tuesday night. However, electoral experts and state officials predicted it was more likely to come on Wednesday morning. In some cases it can take days or even weeks to finalise results as absentee and postal ballots are counted, and occasionally recounted.

It is also likely there will be a wait to know which party will control each of the two chambers of Congress, the Senate and the House of Representatives.

There are four extremely competitive Senate races and 22 toss-up House races, according to the non-partisan Cook Political Report. The Senate map “very likely portents a [Republican] majority” while the battle for the House “remains as close as it’s ever been” wrote CPR’s Erin Covey.

Which states are key to victory?

The most important states to watch are the seven battlegrounds: Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin, which have a combined 93 electoral college votes.

Not every swing state needs to be called for a president to be named. Should Harris or Trump win the so-called blue wall states — Michigan, Pennsylvania and Wisconsin — and North Carolina overnight, for example, that would form a relatively quick path to 270.

North Carolina could be the first battleground to be called since most people vote in person and postal ballots must arrive by election day. A wild card issue this year is the impact of Hurricane Helene, which hit the state hard.

Georgia also counts quickly, but its razor-thin margin of 11,779 in 2020 led to a hand tally and the state was not called for Biden until more than two weeks after the election.

Strength in the blue wall could indicate a candidate is doing well among working-class voters, while a win in Georgia could bode well for having won over Black voters.

Pennsylvania is slow because it cannot start counting postal ballots until election day. Wisconsin also cannot start counting postal ballots until election day, but officials expect a result on Wednesday morning since the tally must continue through the night. Michigan could move more quickly than before since more postal ballots can be processed before election day.

Arizona and Nevada are likely to be the slowest with results. Arizona officials have said it could take 10-13 days to report full results. In Nevada, a lot of people vote by post.

What happened in 2020?

Joe Biden was not declared the victor until Saturday, November 7 2020, four days after election day. AP made the call at 11.26am ET.

The AP began calling races from 7pm on election day starting with Kentucky. Races in battleground states took much longer — with the AP calling North Carolina 10 days after election day and Georgia 16 days later.

Pennsylvania was the state that put Biden over the top, while Georgia and North Carolina were too close to call at that stage. Overall, Biden won six of the states considered battlegrounds this year, with Trump taking only North Carolina.

While Congress was certifying the results of the election on January 6 2021, a mob of violent Trump supporters attacked the US Capitol in an effort to halt the proceedings and overturn Biden’s victory. Democrats cite the events as evidence that Trump threatens democracy if he is re-elected.

In 2016, the AP named Trump the winner over Democrat Hillary Clinton at 2.29am ET on Wednesday, November 9, the day after the election. Wisconsin was the state that put Trump over the top, while Arizona and Michigan were still too close to call.

What is different this time?

The biggest difference is that there is no pandemic.

In 2020, there was a surge in early voting as people tried to avoid catching Covid-19 at the polls on election day.

This complicated the tallying effort for state election authorities because many were not used to handling large volumes of postal ballots, which take longer to tabulate because they need to be opened and verified by election workers. Some states also had social-distancing rules in place for election officials that also slowed counting.

So far, fewer people have voted early — both in person and by post — than in 2020, meaning state election officials could have a more manageable flow of early ballots to process, therefore speeding up results.